Power toothbrushes are well known and widely used home appliances. Typically, these devices are electrically driven, utilizing either a rotary electric drive or a form of reciprocating, vibratory drive. The working element (i.e., the brush) typically is driven to reciprocate either linearly or through a limited rotary motion. In either case, the working element executes a back and forth motion over the teeth and gums. In accordance with one aspect of the present invention, a new and improved powered toothbrush appliance is provided in which the working element is arranged to execute an orbital motion, such that the primary working stroke of the brush over the teeth and/or gums is effectively largely unidirectional. During the return motion of the brush, its orbital path tends to retract it away from the teeth and gums, or at least lessen the pressure during the return stroke. This motion provides a brush stroke which approximates the theoretical ideal, in that the primary working stroke can be unidirectional, from the base of the gums, either upward or downward as the case may be, toward the tips of the teeth. The motion is reversable, of course, so that the working stroke may be in an upward direction for the lower teeth and in a downward direction for the upper teeth.
In one of the most advantageous forms of the invention, motive power is provided by a water driven nutating motor having an orbitally moving output element. Pursuant to one aspect of the invention, in order to minimize the overall length of the application, from the base of the handle to the tip of the brush, the orbital motion of the nutating motor is converted to a rotary motion through an intermediate drive member, and this drive member in turn imparts the desired orbital motion to the working element or brush.
Where somewhat greater overall length of the appliance is not objectionable, the orbital output of the nutating motor may be imparted directly to the working element. The latter arrangement is characterized by greater mechanical simplicity, but requires somewhat greater length in order to achieve an orbital path of proper dimensions at the tip of the working element.
In accordance with a still further aspect of the invention, a powered toothbrush appliance is provided, in which the working element is caused to execute the desired reversable orbital path, being driven, however, by a conventional rotary electric motor, mounted in the handle of the appliance. This has the advantage of extreme simplicity.
In any of the water-powered versions of the new appliance, provision may be made for controllably diverting at least a portion of the motive fluid--water--into the shank of the brush, to be discharged into the bristle area at the head of the brush. This provides a highly efficient moistening and rinsing action, so that brushing with dentifrice and rinsing may be completed in a single, continuous operation, without interruption for obtaining rinse water from another source.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of preferred embodiments of the invention, and to the accompanying drawings.